(i) Field of the Invention
Bt or Bacillus thuringiensis is well known for its specific toxicity to insect pests, and has been used since almost a century to control insect pests of plants. In more recent years, transgenic plants expressing Bt proteins were made which were found to successfully control insect damage on plants (e.g., Vaeck et al., 1987).
Despite the isolation of a number of Bt crystal protein genes, the search for new genes encoding insecticidal proteins continues. Indeed, insecticidal Bt crystal proteins are known to have a relatively narrow target insect range compared to chemical insecticides. Also, having multiple toxins active on the same target insect species allows the use of proteins having different modes of action so that insect resistance development can be prevented or delayed.
(ii) Description of Related Art
Previously, several types of Cry1B-, Cry1J-, and Cry9-proteins were identified (see Crickmore et al., 1998, incorporated herein by reference, for all details).
The new Cry1Bf protein has the closest sequence identity with the Cry1Be protein (Payne et al, 1998, U.S. Pat. No. 5,723,758), but still differs in about 14 percent of the amino acid sequence of its toxic protein fragment with the toxic fragment of the Cry1Be protein.
The closest sequence identity with the Cry1Jd toxic fragment was found in the toxic fragment of the Cry1Jc1 protein (U.S. Pat. No. 5,723,758), but the toxic fragments of both proteins still differ in about 18% of their amino acid sequence.
The closest sequence identity with the Cry9Fa toxic fragment was found with the toxic fragment of the Cry9Ea1 protein as described by Midoh et al. (PCT Patent publication WO 98/26073) and Narva et al. (PCT patent publication WO 98/00546), but the toxic fragments of the Cry9Fa and Cry9Ea proteins still differ in about 21% of their amino acid sequence.